Device and a method for providing electrical energy to an actuator, and an actuator system

ABSTRACT

A method for providing electrical energy to an actuator is disclosed. In at least one embodiment, the method includes having a first voltage (UBUS) from a data bus; ii) converting the electric current to a current having a second voltage that is higher than the first voltage; iii) storing electrical energy of the second electric current; and discharging the stored electrical energy to an actuator. A device is also disclosed for providing electrical energy to an actuator.

PRIORITY STATEMENT

This application is the national phase under 35 U.S.C. §371 of PCTInternational Application No. PCT/EP2006/007320 which has anInternational filing date of Jul. 25, 2006, the entire contents of whichare hereby incorporated herein by reference.

FIELD OF THE INVENTION

Embodiments of the invention generally relate to devices and methods forproviding electrical energy to an actuator, and/or to actuator systems.

BACKGROUND ART

In different applications for automation engineering, the use of sensorsor actuators via data buses for monitoring and controlling of processeshas become very popular. Related cost advantages may be remarkable, inparticular, because the complexity of the wiring and cabling may bereduced, at the same time improving the reliability of operation.

Indeed, the advantages of reducing the need for cabling and wiring havebeen considered to be so important that in some applications employingsystem components requiring an electrical power supply, in addition tothe primary function of data transfer, a secondary function of providingelectrical power through the data bus has been implemented too. This isthe case with the AS-Interface bus, for example.

For actuators, such as valve sets, with relatively high powerconsumption, the “black power cable” next to the “yellow cable” of theAS-Interface bus provides a 24V floating DC supply which is fullyisolated from the data signals. The “black power cable” in anAS-Interface bus is typically rated up to 8 A though the cable itselfcould handle more. With an improved design, currents higher than 8 A canbe drawn, still complying with the AS-Interface specification regardingthe amount of voltage drops in the network.

Unfortunately, part of the advantages gained by the reduced need forcabling or wiring are lost if a separate power cable is needed.

SUMMARY

At least one embodiment of the invention improves devices and methodsfor providing electrical energy to an actuator so that a separate powercabling becomes redundant.

If a device for providing electrical energy to an actuator includes i) aconnection device for receiving a first electric current from a databus, the first electric current having a first voltage, ii) transformerdevice for converting said first electric current to a second electriccurrent having a second voltage that is relatively higher than the firstvoltage, iii) a storing device adapted to store electrical energy ofsaid second electric current; and iv) discharging device adapted todischarge electrical energy stored in said storing means to an actuator,the separate power cabling so far required to operate an actuatorrequiring an operating voltage higher than that available via a data busis no more needed.

If the device for providing electrical energy to an actuator furthercomprises a control device adapted to discharge the discharging device,the moment at which the actuator is used can be better selected. In thismanner, also actuators requiring more instantaneous power than the databus can instantaneously supply can be used, since the smallercontinuously available power that can be taken from the data bus can bestored.

A particularly efficient way to store electrical energy is to store itin capacitive storing device.

If the connection unit includes an AS-Interface connector, the devicefor providing electrical energy to an actuator can be adapted to receiveenergy from the AS-Interface and also the discharging of the actuatormay be carried out in response to a command over the AS-Interface.

BRIEF DESCRIPTION OF THE DRAWINGS

The FIGURE shows a device 50 for providing electrical energy to anactuator 200.

DETAILED DESCRIPTION OF THE EXAMPLE EMBODIMENTS

In the following, an example embodiment of the invention is described inmore detail with reference to the accompanying drawing in the FIGURE.

The FIGURE shows a device 50 for providing electrical energy to anactuator 200. The device comprises a connection unit 51, a transformerunit 52, a storage unit 53 and a discharging unit 54. Even though it ispossible that the device 50 comprises an actuator 200, it isnevertheless not necessary. It suffices that the device 50 isconnectable to an actuator 200, preferably via an actuator connector.

The actuator 200 may be any kind of actuator. In the example embodiment,it nevertheless includes a step motor, a magnet valve, an interlockingor interlocking-releasing electromagnet, or a piezoelectric forcetransducer.

The connection unit 51 is adapted to receive a first electric currentfrom a data bus 100, the first electric current thus having a firstvoltage UBUS which may be less or equal to the data bus voltage. Theconnection unit 51 may be carried out using a connector connected to acable, or with a separate wiring. It provides the first electric currentto the transformer unit 52, likewise it provides the ground potentialGND for the other units.

A non-limiting example of a data bus 100 suitable for carrying out theinvention is the AS-Interface (ASI), in which case the connection unit51 comprises an AS-Interface connector. The data bus of an AS-Interfaceincludes two wires 101, 102, one of which is the ground line 102 and theother of which is the data line 101, between of which the voltageU_(BUS)=30 Volt.

The transformer unit 52 is adapted to convert the first electric currentto a second electric current having a second voltage U_(C) that isrelatively higher than the first voltage U_(BUS).

If the direction of the first electric current changes, i.e. that thefirst electric current is an A.C. current and not an D.C. current, thetransformer unit 52 preferably consists of a transformer 52B including aprimary coil 321 and a secondary coil 323 and preferably also a ferriticcore 322, and optionally also an A.C. to D.C. converter 52C, dependingon the kind of the storage unit 53, i.e. depending on whether thestorage unit 53 is adapted to store electrical energy of an A.C. currentor of a D.C. current. The A.C. to D.C. converter 52C converts,preferably by using four diodes 331, 332, 333 and 334 an A.C. current toa D.C. current and ensures that electrical energy that will be releasedfrom the storage unit 53 will not be led back to other parts of thetransformer unit 50 and to the data bus 100.

If the direction of the first electric current does not change, i.e.that the first electric current is a D.C. current and not an A.C.current, the transformer unit 52 may additionally comprise a D.C. toA.C. converter 52A between the connection unit 51 and the transformer52B. A possible circuit for an D.C. to A.C. converter 52A includes twoswitches—such as transistors 304, 314—that can be switched in apredetermined manner—preferably with the help of timing components 301,302, 303, 311, 312, 313—to form an A.C. current, for example, by feedingthe a D.C. voltage different ends of the primary coil 321 of thetransformer 52C.

Since suitable D.C. to A.C. converters are available on the market atthe time of filing of the patent application, it is to be understoodthat the manner in which the skilled person can carry out the inventiondoes not require an in-depth knowledge of the working principle of anD.C. to A.C. converter.

In the AS-Interface, the voltage between the lines 101, 102 is a D.C.voltage and therefore the first electrical current is a D.C. current.

The storage unit 53 is adapted to store electrical energy of the secondelectric current. The storage unit 53 is preferably a capacitive storingunit which is extremely well suitable for storing electrical energycontained in a D.C. current. A capacitive storing unit may include oneor more capacitors 53 that are connected in series or in parallel.

Also other kinds of systems for storing electrical energy can be used inthe storage unit 53, depending whether storage of electrical energycontained in an A.C or in a D.C. current is desired. As a particularexample, at least one rechargeable battery where energy is storedchemically, can be used as the storing unit 53 as well.

The discharging unit 54 is adapted to discharge electrical energy storedin the storage unit 53 to an actuator 200. The discharging unit 54 maycomprise a switch 343, such as a transistor or a thyristor, a resistor341 and a diode 340. Upon receiving a discharge command, e.g. in theform of a control voltage TRG, the switch is activated and electricalenergy stored in the storage unit 53 is released to the actuator 200.

The circuitry of the device 50 is preferably connected to both the dataline 101 and the ground line 102. The data line 101 is preferablyconnected to a control unit 110 that is adapted to discharge thedischarging unit 54 preferably by setting a control voltage TRG. Thecontrol unit 110 may be adapted to discharge the discharging unit 54 inresponse to a command (DATA) received via the data bus 100, or uponmeeting predefined criteria, such as passing of enough current to thetransformer unit 52 indicating that the charge status of the energystoring unit 53 is enough to actuate the actuator 200.

To this end, the control unit 110 may include a protocol stack adaptedto communicate over the AS-Interface, i.e. to receive or send 4-bits ofuser data or as in the “Combined Transaction Type 1”, to receive or send16-bit analog values.

Even though the invention was described using a non-limiting embodiment,the true scope of the invention can be studied from the scope of theattached patent claims.

Example embodiments being thus described, it will be obvious that thesame may be varied in many ways. Such variations are not to be regardedas a departure from the spirit and scope of the present invention, andall such modifications as would be obvious to one skilled in the art areintended to be included within the scope of the following claims.

1. A device for providing electrical energy to an actuator, comprising:connection unit to receive a first electric current from a data bus, thefirst electric current having a first voltage; and transformer unit toconvert said first electric current to a second electric current havinga second voltage that is relatively higher than said first voltage;storing unit to store electrical energy of said second electric current;and discharging unit to discharge electrical energy stored in saidstoring unit to an actuator.
 2. A device according to claim 1, furthercomprising control unit to discharge said discharging unit.
 3. A deviceaccording to claim 2, wherein said control unit is responsive to acommand received from the data bus.
 4. A device according to claim 3,wherein said control unit comprises a protocol stack adapted tocommunicate over the AS-Interface.
 5. A device according to claim 1,wherein the storing unit is a capacitive storing unit.
 6. A deviceaccording to claim 1, wherein said connection unit comprises anAS-Interface connector.
 7. An actuator system, comprising: an actuator;and a device as claimed in claim 1, for providing electrical energy tosaid actuator.
 8. An actuator system according to claim 7, wherein saidactuator comprises at least one of a step motor, a magnet valve, aninterlocking or interlocking-releasing electromagnet, and apiezoelectric force transducer.
 9. A method for providing electricalenergy to an actuator, comprising: receiving an electric current havinga first voltage from a data bus; converting the electric current to acurrent having a second voltage that is relatively higher than the firstvoltage; storing electrical energy of the second electric current; anddischarging said stored electrical energy to an actuator.
 10. A methodaccording to claim 9, wherein said storing of electrical energy isperformed using a capacitive storing device.
 11. A device for providingelectrical energy to an actuator, comprising: means for receiving anelectric current having a first voltage from a data bus; means forconverting the electric current to a current having a second voltagethat is relatively higher than the first voltage; means for storingelectrical energy of the second electric current; and means fordischarging said stored electrical energy to an actuator.
 12. A deviceaccording to claim 11, further comprising control means for dischargingsaid means for discharging.
 13. A device according to claim 12, whereinsaid control means is responsive to a command received from the databus.
 14. A device according to claim 13, wherein said control meanscomprises a protocol stack adapted to communicate over the AS-Interface.15. A device according to claim 11, wherein the storing means includes acapacitive storing device.
 16. A device according to claim 11, whereinsaid connection means comprises an AS-Interface connector.
 17. Anactuator system, comprising: an actuator; and a device as claimed inclaim 11, for providing electrical energy to said actuator.
 18. Anactuator system according to claim 17, wherein said actuator comprisesat least one of a step motor, a magnet valve, an interlocking orinterlocking-releasing electromagnet, and a piezoelectric forcetransducer.